1. Field of the Invention
This invention relates to a thermosetting resin composition consisting essentially of a prepolymer having more than one double bond of the styrene type at the terminals of the molecule and a vinyl monomer.
An object of this invention is to provide a thermosetting resin composition which can form a cured material possessing improved mechanical properties, such as impact resistance, resistance to chemicals, air-setting properties and so on.
2. Description of the Prior Art
Thermosetting resins that undergo a curing reaction due to the copolymerization of (1) a prepolymer having a double bond capable of radical polymerization with (2) a vinyl monomer, are known, and reference can be made to unsaturated polyesters as typical. However, these have disadvantages in that they shrink greatly during curing and the cured products are poor in impact resistance. With respect to a thermosetting resin improved in, especially, its impact resistance, for example, Japanese Patent Publication Nos. 15988/1970 and 25178/1970 disclose a resin with a terminal diacryl group in the molecule. Although such a resin has favorable properties, it has an insufficient air-setting property. The resin becomes sticky because of the insufficient setting of the surface when in contact with air.